Data security

Computer Science AS · Security, privacy and data integrity. The idea in plain words, the rules to remember, the mistake to avoid and a worked example, written and checked by Mega Lecture.

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The idea

Three terms are easy to confuse. Security means protecting data from loss, damage or unauthorised access. Privacy means keeping personal data away from people who have no right to see it. Integrity means the data is accurate, complete and up to date.

Both the data and the computer system need protection. Threats come mainly through networks and the internet: malware such as viruses and spyware, hackers, phishing and pharming.

For each threat, know a measure that reduces the risk. Some measures control who gets in (user accounts, passwords, biometrics, firewalls). Others limit the damage after someone gets in (encryption, access rights).

Rules to remember

Virus: malicious code that copies itself and can delete or corrupt files. Spyware: secretly records what the user does, such as key presses, and sends it to a third party.
Phishing: a fake email or message with a link that tricks the user into giving personal details.
Pharming: malicious code or a changed DNS entry sends the user to a fake website even when the correct address is typed.
Firewall: checks incoming and outgoing network traffic against a set of rules and blocks traffic that does not meet them.
Encryption: turns data into ciphertext that cannot be understood without the key. It does not stop the data being stolen or deleted.
Digital signature: shows who sent a document and that it was not changed on the way.
Access rights: each user or group may only read, write or delete the data their job needs.

Common mistake

Students write that encryption stops hackers from getting the data. It does not prevent access or theft; it only makes the stolen data meaningless without the key.

Worked example

A user types the correct web address of an online shop, but a copy of the site opens and records the card details entered. Name the threat and one way to reduce the risk.

The user typed the right address, so no fake link was clicked. This rules out phishing.
Being redirected to a fake site from a correct address is pharming, caused by malicious code on the computer or a changed DNS entry.
Up-to-date anti-malware software can remove the code, and checking for https and a valid digital certificate helps the user notice the fake site.

Answer: Pharming; use up-to-date anti-malware software and check the site's certificate before entering details.

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